Why Deformity Correction Analysis Is Critical For Foot And Ankle Surgeons

As foot and ankle surgeons, we are well-versed on the normal radiographic parameters of the foot and ankle. In our daily work, we discuss angles such as: Meary’s, calcaneal inclination, intermetatarsal, or Kite’s. We memorize these angles to understand radiographic abnormalities. Accordingly, our clinical analysis of the foot and ankle, with an understanding of normal joint range of motion and biomechanics, enables us to offer expertise. Each of these are important for deciding on treatment plans for our patients and surgical procedure selection. However, less often in our education do we hear discussions of mechanical axis deviation, what a magnitude of deformity is, or what osteotomy rules are. These are basic principles in deformity correction analysis, and something in which I believe every foot and ankle surgeon should receive training in.

I was fortunate to attend a residency program that exposed me to these principles, and then had the privilege to complete my fellowship at a world-renowned center for deformity correction analysis. As a result, I have seen firsthand the importance of learning these principles for all foot and ankle treatments.

These principles enable us to understand WHY a lateral closing wedge osteotomy (Dwyer) can correct a calcaneal varus deformity, preoperatively plan the size of the wedge osteotomy, choose the correction plane in which to make the osteotomy, and conceptualize WHY there is obligatory lateral translation of the calcaneus.¹ We can analyze hallux valgus deformities with an understanding of the location of the apex of deformity, understand WHY we do not complete our osteotomy or correction at that level, and why there is again obligatory translation, whether for a distal osteotomy is performed or a first tarsometatarsal arthrodesis (Lapidus).¹ Once we understand how these principles affect more common procedures, we may then extrapolate the principles to more complicated conditions, and create appropriate treatment plans for patients with severe deformities. Full deformity analysis also enables us as foot and ankle surgeons to understand implications of more proximal joints, such as the knee or hip, and deformities of the tibia and femur.¹

The step-by-step process for analysis is “Mapping the ABC’s,” the basis of our alphabet and the basis of our understanding of deformity.¹ For those looking to learn more about deformity correction I would recommend the textbook The Art of Limb Alignment, Tenth Edition,¹ as well as attending the Baltimore Limb Deformity Course held every August.²

Dr. Millonig is a fellowship-trained foot and ankle surgeon specializing in deformity correction and minimally invasive surgery. She practices at East Village Foot and Ankle Surgeons in Des Moines, IA. She is an Associate of the American College of Foot and Ankle Surgeons. Dr. Millonig has held multiple leadership positions in numerous national committees with the American College of Foot and Ankle Surgery, American Public Health Association, and the American Podiatric Medical Association.

References

1. Standard SC, Herzenberg JE, Conway JD, Siddiqui NA, McClure PK, Assayag MJ. The Art of Limb Alignment. (10^th ed.) Baltimore: Rubin Institute for Advanced Orthopedics, Sinai Hospital of Baltimore; 2021.

2. Baltimore Limb Deformity Course. International Center for Limb Lengthening website. Available at: https://www.limblength.org/about-us/physician-education/baltimore-limb-deformity-course/ . Accessed September 17, 2021.